Dyno day, Now with figures!!! |
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Dyno day, Now with figures!!! |
emerygt350 |
Nov 20 2021, 02:32 PM
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#1
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Advanced Member Group: Members Posts: 2,081 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
Just got back from the Dyno. We were able to tune the mps reasonably well. Still have a little leanness at wot and lower rpms and richness at wot at high rpms but overall pretty smooth. Waiting to get the figures from the shop. If I remember right it was 77 horsepower and 105 lbs of torque at the wheels. I am running big 225/50r16s so I suspect I would pick up some more with lighter stock rims and tires....
I will post the graphs as soon as I get them. |
Van B |
Nov 22 2021, 02:39 PM
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#2
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Senior Member Group: Members Posts: 1,582 Joined: 20-October 21 From: Maryland Member No.: 26,011 Region Association: None |
More resistance in the plug means more energy build up before the spark can jump the gap. So, a more powerful can overcome the sparkplug resistance quicker and provide more arc energy to the spark itself... but there's a lot of other assumption on that as well: plug wires, etc. But treating the coil as a constant, a higher resistance plug can alter the actual spark timing just ever so slightly. Going to Coil On Plug (COP) is what gave manufacturers the ability to really tune engines for efficiency. Even differing length of plug wires varies resistance between cylinders.
Regardless, you want to be a little rich at high RPM and WOT... the last place you want detonation is during the most stressful parameters for engine operation. Being a little lean off the bottom can give a more snappy throttle response too. The problem you run into when trying to nail the AFR is that you have no forgiveness in the fuel. I'm sure we all run premo fuel, but let's say you fill up one day and the premium is 1 octane point lower than what you used for tuning and you dialed in a perfect 14.7:1 AFR... well now you have a detonation problem. So, there's no point in running a street engine at 14:1 AFR. I'd like to know the ratios you were seeing at "a little lean, and a little rich" for my own curiosity. But if you're even 12:1, I'd say you're just fine. |
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